    var show_num = [];
    draw(show_num);
    function dj(){
        draw(show_num);
    }
    function sublim(){
    var val=document.getElementById("text").value;
               var num = show_num.join("");
               if(val==''){
                   alert('请输入验证码！');
               }else if(val == num){
                   alert('提交成功！');
                   document.getElementById(".input-val").val('');
                   draw(show_num);

               }else{
                   alert('验证码错误！\n你输入的是:  '+val+"\n正确的是:  "+num+'\n请重新输入！');
                   document.getElementById("text").value='';
                   draw(show_num);
               }



             }
    function draw(show_num) {
           var canvas_width=document.getElementById('canvas').clientWidth;
           var canvas_height=document.getElementById('canvas').clientHeight;
           var canvas = document.getElementById("canvas");//获取到canvas的对象，演员
           var context = canvas.getContext("2d");//获取到canvas画图的环境，演员表演的舞台
           canvas.width = canvas_width;
           canvas.height = canvas_height;
           //var sCode = "A,B,C,E,F,G,H,J,K,L,M,N,P,Q,R,S,T,W,X,Y,Z,1,2,3,4,5,6,7,8,9,0,q,w,e,r,t,y,u,i,o,p,a,s,d,f,g,h,j,k,l,z,x,c,v,b,n,m";
           var sCode = "1,2,3,4,5,6,7,8,9,0";
           var aCode = sCode.split(",");
           var aLength = aCode.length;//获取到数组的长度

           for (var i = 0; i <= 3; i++) {
               var j = Math.floor(Math.random() * aLength);//获取到随机的索引值
               var deg = Math.random() * 30 * Math.PI / 180;//产生0~30之间的随机弧度
               var txt = aCode[j];//得到随机的一个内容
               show_num[i] = txt;
               var x = 10 + i * 20;//文字在canvas上的x坐标
               var y = 20 + Math.random() * 8;//文字在canvas上的y坐标
               context.font = "bold 23px 微软雅黑";

               context.translate(x, y);
               context.rotate(deg);

               context.fillStyle = randomColor();
               context.fillText(txt, 0, 0);

               context.rotate(-deg);
               context.translate(-x, -y);
           }
           for (var i = 0; i <= 5; i++) { //验证码上显示线条
               context.strokeStyle = randomColor();
               context.beginPath();
               context.moveTo(Math.random() * canvas_width, Math.random() * canvas_height);
               context.lineTo(Math.random() * canvas_width, Math.random() * canvas_height);
               context.stroke();
           }
           for (var i = 0; i <= 30; i++) { //验证码上显示小点
               context.strokeStyle = randomColor();
               context.beginPath();
               var x = Math.random() * canvas_width;
               var y = Math.random() * canvas_height;
               context.moveTo(x, y);
               context.lineTo(x + 1, y + 1);
               context.stroke();
           }
       }
    function randomColor() {//得到随机的颜色值
           var r = Math.floor(Math.random() * 256);
           var g = Math.floor(Math.random() * 256);
           var b = Math.floor(Math.random() * 256);
           return "rgb(" + r + "," + g + "," + b + ")";
       }
